7
I can't speak to why they made it an option, but it is frequently requested so I guess that's why the code is in there.
It isn't an option you can turn on during the install, you have to go edit the code itself to turn it on. My guess is they did this to force people to consider the security repurcusions of enabling this.
If turned on correctly, users can select if they want a password remembered or not, it is not automatic.